Newly raised anti-c-Kit antibody detects interstitial cells of Cajal in the gut of chicken embryos

The gut peristaltic movement, a wave-like propagation of a local contraction, is important for the transportation and digestion of ingested materials. Among three types of cells, the enteric nervous system (ENS), smooth muscle cells, and interstitial cells of Cajal (ICCs), the ICCs have been thought to act as a pacemaker, and therefore it is important to decipher the cellular functions of ICCs for the understanding of gut peristalsis. c-Kit, a tyrosine kinase receptor, has widely been used as a marker for ICCs. Most studies with ICCs have been conducted in mammals using commercially available anti-c-Kit antibody. Recently, the chicken embryonic gut has emerged as a powerful model to study the gut peristalsis. However, since the anti-c-Kit antibody for mammals does not work for chickens, cellular mechanisms by which ICCs are regulated have largely been unexplored. Here, we report a newly raised polyclonal antibody against the chicken c-Kit protein. The specificity of the antibody was validated by both Western blotting analyses and immunocytochemistry. Co-immunostaining with the new antibody and anti- smooth muscle actin (SMA) antibody successfully visualized ICCs in the chicken developing hindgut in the circular muscle- and longitudinal muscle layers: as previously shown in mice, common progenitors of ICCs and smooth muscle cells at early stages were double positive for SMA and c-Kit, and at later stages, differentiated ICCs and smooth muscle cells exhibited only c-Kit and SMA, respectively. A novel ICC population was also found that radially extended from the submucosal layer to circular muscle layer. Furthermore, the new antibody delineated individual ICCs in a cleared hindgut. The antibody newly developed in this study will facilitate the study of peristaltic movement in chicken embryos.